It has heretofore been known that medals for a game machine, such as a slot machine, and an abrasive are mixed and then stirred to polish the medals, and that the abrasive is thereafter separated from the medals and mixed with medals again for reuse.
The prior art, however, has involved the problem that, when the medals and the abrasive are accepted in order to polish the former by the stirring, excessive forces act on the medals to deform them. Another problem has been that a polishing machine increases in height due to requirements of the treatment and its external appearance does not blend well with the surroundings. A further problem has been that, since the abrasive for use is usually made of a plastic material, the abrasive becomes electrostatically charged in the polishing operation and sticks to the medals and is not easily separated therefrom in an abrasive separation unit.